Precise determination of thermal expansion coefficients observed in 4H-SiC single crystals

摘要: The coefficient of thermal expansion (CTE) SiC single crystals is important, in particular, for both designing device assembly and controlling stress distributions heteroepitaxial thin film structures grown onto substrates. We have performed very precise measurements the CTEs comprising 4H polytype PVT-grown NIPPON Steel Corporation a temperature range from 123 K to 473 using laser interferometry method. This method allows us directly measure dependent variation crystal volume with much higher accuracy, enables straightforwardly obtain practical information CTE data. Furthermore order discuss behavior wider at temperatures up 1573 been also measured dilatometer obtained nitrogen-doped 4H-SiC increases continuously 0.8 ppm/K 3.1 273 423 respectively, further 5.4 1273 K. conclude our data that variations are likely be almost independent axis directions